This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. We have begun to examine both receptors and signaling molecules displayed on beads for flow cytometry (Nolan and Sklar, 1998;Sklar et al. 2000). We have shown conditions under which his-tagged receptors may be bound to Ni2+ beads and bind ligand. We have also shown that solublized receptors may be reconstituted with heterotrimeric G proteins (subunits from Neubig) and arrestins (Prossnitz) for fluorescence, and potentially for flow cytometric analysis. We have attempted to use arrestin, receptors, as well as biotinylated receptor tail peptides as bait on beads. We are examining biotinylated anti-his antibodies instead of chelated Ni2+ beads.